Parts feeding apparatus and parts feeding process

ABSTRACT

To provide a compact parts feeding apparatus capable of reducing the parts stock in the line, and facilitate the exchange between different kinds of devices, a first transfer unit 200A of a transferring and positioning arrangement 200C of a parts feeding apparatus 200, transfers a tray T carrying parts PB upward in a first direction Z1 from a conveyor arrangement 14. A positioning unit 200D positions the tray T carrying the parts PB in a determined position within the assembly range of an assembling body 10 of the first transfer unit 200A. A second transfer unit 200B descends in a second direction Z2 opposite to the first direction, to transfer the positioned tray T to the first transfer unit 200a or to discharge the tray T after it has been emptied of parts onto the conveyor arrangement 14.

This application is a continuation of application Ser. No. 08/394,945filed Feb. 24, 1995, now U.S. Pat. No. 5,672,040.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a parts feeding apparatus and partsfeeding process for feeding a plurality of different kinds of parts tobe assembled into a predetermined piece of work.

2. Description of the Related Art

In case a precise and complex device such as the mechanical deck of atape recorder or VTR is to be assembled, a plurality of kinds of partsare assembled by an assembling robot which is usually fed with the partsby a parts feeding apparatus. The number of parts to be assembled by theprior art assembling robot is usually limited to one or two, forexample.

This type of parts feeding apparatus is exemplified by a parts feeder, atray changer, a magazine feeder or a hoop feeder. One or two of theseparts feeding arrangements is usually included in the assembling robot.The thus built in parts feeding apparatus feeds the assembling robotwith the parts for assembly therein.

However, this type of parts feeding apparatus is almost always arrangedto handle specific type of parts whereby when the parts to be assembledare changed in accordance with a change in the kind of device beingassembled, the parts feeding apparatus and the robotic hands have to bemanually changed or adjusted. Thus, the following problems arise withthe prior art parts feeding apparatus.

In the case fourteen kinds of parts (for example) are to be assembled toform a given piece of work, fourteen different parts feeding apparatushave to be used and thus enlarges total size of the arrangementdrastically. Further, in order to allow the assembling robot to take theindividual parts from the fourteen different parts feeding, the robothas to have a large operating range so that its body is accordinglyenlarged.

If, on the other hand, one or two parts are to be assembled in oneassembling robot cell by dividing the steps, the line space is enlargedto deteriorate the space efficiency. In order to minimize the feedinginterval (or time) and number of the parts, moreover, the parts to bestocked in the parts feeding apparatus has to be retained in a properamount, thus increasing the parts stock in the assembly line. At thetime of changing the device kinds, on the other hand, the parts feedingapparatus and the robot hands of the assembling robot have to be timeconsumingly manually exchanged and adjusted.

Therefore, the present invention has been conceived to solve theabove-specified problems and has an object to provide a parts feedingapparatus capable of sparing space, reducing the parts stock in the lineand easily coping with a change in the device being assembled.

SUMMARY OF THE INVENTION

The object of this invention to provide a parts feeding apparatus forfeeding parts for a given piece of work, on a tray to an assembling bodyfor assembling the parts, comprising: conveyor means for conveying saidparts carrying tray to said assembly body or from the same to theoutside; and transferring and positioning means for transferring andpositioning a plurality of said trays, which are conveyed by saidconveyor means to said assembling body, wherein said transferring andpositioning means includes: a first transfer unit for transferring saidparts carrying tray upward in a first direction from said conveyormeans; a positioning unit for positioning said parts carrying tray fromsaid first transfer unit in a determined position within the assemblingrange of said assembling body; and a second transfer unit either fortransferring said parts carrying tray positioned in said determinedposition, downward in a second direction reversed from said firstdirection, to said first transfer unit or for discharging said trayemptied of said parts toward conveyor means.

Another object of this invention is a parts feeding process for feedinga plurality of parts to be assembled with into a predetermined piece ofwork, to an assembling body for assembling said parts, comprising: thestep of taking a tray carrying said parts necessary for the assemblyinto said assembly body; the step of transferring the taken and partscarrying tray upward in a first direction and positioning the same; thestep of further transferring said taken and parts carrying tray andpositioning within the operating range of said assembly body; the stepof transferring, after the parts carrying tray positioned in theoperating range of said assembly body has its parts necessary for saidassembly removed by said assembling body, either a parts carrying trayor said tray which is emptied of said parts' downward in a seconddirection opposite from to said first direction; and the step of againtransferring said parts carrying tray upward in said first direction toposition the same within the operating range of said assembling body andfor discharging said tray emptied of said parts from the inside of saidassembling body.

According to the above-specified construction, by the action of theconveyor means, the tray carrying the parts is conveyed to or from theassembling body.

Moreover, the transferring and positioning means transfers and positionsthe plurality of trays, which are conveyed to the assembling body bysaid conveyor means, in the assembly body. The first transfer unit ofthis transferring and positioning means moves the parts carrying trayupward in the first direction from the conveyor means.

The positioning unit positions the parts carrying tray from the firsttransfer unit in the determined position within the assembling range ofthe assembling body.

The second transfer unit transfers the positioned and parts carryingtray downward in the second direction reversed from the first direction,to the first transfer unit. Alternatively, the second transfer unittransfers the positioned tray emptied of its parts, downward in thesecond direction to the conveyor means.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a top plan view showing a multi-kind small-quantity productiontype assembly system equipped with a preferred embodiment of the partsfeeding apparatus of the present invention.

FIG. 2 is a top plan view showing an assembly cell (or robot cell)equipped with the preferred embodiment of the parts feeding apparatus,as shown in FIG. 1.

FIG. 3 is a side elevation of the robot cell, as seen in the directionof Q1 of FIG. 2.

FIG. 4 is a side elevation of the robot cell, as seen in the directionof Q2 of FIG. 2.

FIG. 5 is a perspective view showing a take-in (induction) unit of theparts feeding apparatus of the present invention.

FIG. 6 is a perspective view showing a take-out discharge) unit of theparts feeding apparatus of the present invention.

FIG. 7 is a top plan view showing an upper stage conveyor of a partsfeeding conveyor.

FIG. 8 is a top plan view showing a lower stage conveyor of the partsfeeding conveyor.

FIG. 9 is a perspective view showing an example of the components of aportion of the parts feeding apparatus.

FIG. 10 is a perspective view showing an example of a portion of theelements of a take-in unit of the parts feeding apparatus.

FIG. 11 is a perspective view showing an example of a portion of theelements of a take-out unit of the parts feeding apparatus.

FIG. 12 is a perspective view showing a return elevator of the take-outunit.

FIG. 13 is a top plan view showing a hanger of the take-in unit and thetake-out unit.

FIG. 14 is a top plan view showing a separator of the take-in unit andthe take-out unit.

FIG. 15 is a top plan view showing an upper stage separator and apositioning unit of the take-out unit.

FIG. 16 is a side elevation showing a set of sensors of the take-inunit.

FIG. 17 is a diagram showing a hanger upper stage stop position sensorof FIG. 16.

FIG. 18 is a diagram showing a hanger stock area position sensor.

FIG. 19 is a diagram showing a hanger lower stage stop position sensor.

FIG. 20 is a diagram showing a hanger upper limit sensor.

FIG. 21 is a diagram showing a hanger lower limit sensor.

FIG. 22 is a side elevation showing a set of sensors of the take-outunit.

FIG. 23 is a diagram showing a hanger standby position sensor.

FIG. 24 is a diagram showing a hanger intermediate stage stop positionsensor.

FIG. 25 is a diagram showing a hanger lower stage stop position sensor.

FIG. 26 is a diagram showing a hanger upper limit sensor.

FIG. 27 is a diagram showing a hanger lower limit sensor.

FIG. 28 is a top plan view showing a set of tray detecting sensors inthe take-in unit and the take-out unit.

FIG. 29 is a diagram showing the detection of the tray in the take-outupper stage separator.

FIG. 30 is a diagram showing the tray detection in take-out intermediatestage and upper stage separators.

FIG. 31 is a diagram showing an example of the operations of the partsfeeding apparatus, in which the parts are taken out from the tray in thepositioning unit by the robot turret head.

FIG. 32 is a diagram showing the state in which the tray is transferredfrom the upper stage separator of the take-in unit to the upper stageseparator of the take-out unit.

FIG. 33 is a diagram showing the state, in which the tray is transferredto the upper stage separator in the take-out unit by the hanger.

FIG. 34 is a diagram showing the state, in which the tray is transferredto the lower stage separator of the take-in unit by the return elevatorin the take-out unit.

FIG. 35 is a diagram showing that the tray emptied of parts is to betransferred to the lower stage conveyor so that it may be discharged.

FIG. 36 is a diagram showing the state, in which a new tray is to beadded from the outside to a circulation loop formed of the take-in unitand the take-out unit.

FIG. 37 is a diagram showing the state, in which the newly added tray isto be circulated along the circulation loop.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention will be described indetail in the following with reference to the accompanying drawings.

Incidentally, the embodiment to be described is a preferred specific oneof the present invention and is accordingly restricted by a variety oftechnically preferable limitations. However, the scope of presentinvention should not be considered limited thereby, unless it isspecified in the following description.

Assembling System

FIG. 1 shows an assembling system for multi-kind and small-quantityproduction, which is equipped with a preferable embodiment of a partsfeeding apparatus of the present invention. This assembling system isschematically constructed to include an assembling robot unit 100, aparts feeding conveyor 14, an assembling conveyor 54 and parts feedingunits 200. This assembling system is an apparatus for the multi-kind andsmall-quantity production, which is enabled to assemble fourteen parts(or fifteen or sixteen parts according to the thickness of a tray) for awork in one of robot cells 51 of the assembling robot unit 100 byfeeding those parts to the robot cell 51. In the shown embodiment, theassembling robot unit 100 is equipped with three assembling robot cells51. These robot cells 51 are also called the assembly bodies.

Each robot cell 51 is set with the parts feeding unit 200 of the presentinvention. The parts feeding conveyor 14 and the assembling conveyor 54are arranged in parallel with the assembling robot unit 100.

Parts Feeding Conveyor 14

Here will be described the parts feeding conveyor 14.

This parts feeding conveyor 14 is composed, for example, of three partsfeeders 52, a transfer conveyor 53, return units 55a and 55b, andintermediate return units 56a and 56b. The parts feeding conveyor 14 isprovided for conveying both trays T carrying parts and pallets Pcarrying other kinds of parts in the flow direction A1 of parts. Thereturn units 55a and 55b are respectively arranged at the front endportion and the rear end portion of the transfer conveyor 53. Moreover,the intermediate return units 56a and 56b are respectively arranged atthe front end portion and the rear end portion of the three partsfeeders 52. On the other hand, a loading station 58 is disposeddownstream of the return unit 55a.

On the other hand, the assembling conveyor 54 is provided for conveyingpallets PA carrying pieces of work or works W as they will be referredto hereinafter, to the individual robot cells 51 in the direction ofarrow A2. The assembling conveyor 54 is composed of return units 57a and57b and a take-out station 59. This take-out station 59 is a unit fortaking out the completed assembly of the plurality of kinds of parts forthe base (or chassis) of a VTR device, for example, from the assemblingconveyor 54.

The parts to be assembled into the work W are carried by the trays T andthe feed pallets P. The trays T can be exemplified by foamed polymertrays. The trays T carrying the parts and the pallets P for the partsfeeders 52 can be brought from the loading station 58 to the partsfeeding conveyor 14 and transferred by the transfer conveyor 53. Thepallets P thus transferred are taken into and arrayed by a predeterminedone of the parts feeders 52 so that they are loaded with a predeterminedkind of parts. Then, the pallets P are returned to the conveyor 53 untilthey are fed to the robot cells 51. On the other hand, the trays T arealready loaded with the parts, when they are brought to the loadingstation 58, so that they are directly fed to the robot cells 51 or theassembling cells.

The assembling pallet PA thus supplied from the take-out station 59 ispositioned in the predetermined robot cell 51. For the work W on thepallet PA, moreover, the predetermined kinds of parts on the pallet P orthe tray T are assembled by the assembling robot 10 of the robot cell51. When the parts necessary for the assembly are exhausted duringassembly, the tray T or the pallet P is returned by the robot cell 51 tothe parts feeding conveyor 53 so that it is returned by the return unit55b and conveyed in the direction of arrow A3 by the lower stageconveyor of the conveyor 53.

The pallet P is returned by the intermediate return unit 56a to theupper stage conveyor of the parts feeding conveyor 14 and is taken up bythe parts feeder 52. On the other hand, the tray T is returned by thereturn unit 55a to the upper stage conveyor until it is replaced by anew tray carrying the parts at the loading station 58.

The pallet P supplied with the parts and the tray T carrying the partsare transferred again to the robot cells 51 by the conveyor 53. At thistime, the robot cells 51 are awaiting the pallet P and the tray Tnecessary for the assembly.

The pallet P and tray T unnecessary or mistaken in order is passed, ifat the predetermined position, through the robot cells so that they arecirculated till they are required by the return unit 55b and theintermediate return unit 56a.

On the other hand, when the works W are changed in the kinds to exchangethe kind of device to be assembled of the parts, the pallets P and thetrays T for the former device kind are unloaded from the loading station58, and this station 58 is loaded with the pallets P and the trays T forthe next kind. At this time, the parts of the previous kind in thehoppers of the parts feeders 52 are replaced by the parts for thesubsequent kind. However, the common parts are left in the hoppers.

Thus, the kinds of device can be interchanged by replacing the palletheads and the pallets, which are stocked in the super-pallet changers inthe robot cells 51.

Robot Cell 51

Reference will be made to FIGS. 2 to 4. In FIGS. 2 to 4 showing theparts assembling robot cell 51 (or assembling body): FIG. 2 is a topplan view of the robot cell 51; FIG. 3 is a side elevation taken in thedirection of arrow Q1 of FIG. 2; and FIG. 4 is a side elevation taken inthe direction of arrow Q2 of FIG. 2. This robot cell 51 is given aconstruction, as will be described in the following. As shown in FIGS. 3and 4, the robot 10 of the robot cell 51 is equipped with a turret head12 capable of mounting six hands, for example, at the maximum. Thesehands are mounted for gripping the parts which are carried on theaforementioned pallet P or tray T.

As shown in the top plan view of FIG. 2, there are extended through theframe 51a of the robot cell 51 an upper stage conveyor 14a and a lowerstage conveyor 14b of the parts feeding conveyor 14. Across the frame51b, moreover, there is extended the assembling conveyor 54. Thisassembling conveyor 54 is also equipped with upper and lower stages 13aand 13b. A super-pallet changer 15 has the turret heads stocked thereinfor the fourteen kinds of parts, so that the necessary turret heads canbe automatically exchanged between the super-turret changer 15 and theturret head 12.

A pallet lifter 20 of FIG. 2 is provided for taking the pallet Pcarrying the parts from the upper stage conveyor 14a of the partsfeeding conveyor 14 into the robot cell 51. For taking in the pallet,there is used a pusher 18. A pallet buffer 19 for buffering the pallet Pthus taken in is disposed in the vicinity of the pallet lifter 20.

A pallet positioning unit 25 is one for positioning the pallet P fortaking up the parts carried on the pallet P by the robot 10. The partsfeeding unit 200 is preferably arranged in the frame 51a of the robotcell 51 and is equipped with two elevator units 21a and 21b. Eachelevator unit 21a or 21b of the parts feeding unit 200 is used to feedthe plurality of aforementioned trays T sequentially and circularly inthe assembling cell 51.

The aforementioned pallet P of FIG. 1 is fed in the parts feeder 52 withthe parts by vibrations. On the contrary, the tray T is preferably usedto feed the parts which cannot be vibratorily fed. As shown in FIG. 2,the assembling conveyor 54 is equipped with an assembling palletpositioning unit 17. This positioning unit 17 positions the assemblingpallets PA so as to assemble the parts for the work.

In the robot cell 51 of FIGS. 2 to 4, the following operations arecarried out. The pallet P and the tray T are conveyed while carrying theparts by the upper stage conveyor 14a of the parts feeding conveyor 14are discriminated by the pallet lifter 20. If this discriminationreveals that the pallet P carrying the necessary parts has reached thepallet lifter 20, the pallet P is lifted up as it is (i.e., in adirection normal to the sheet of FIG. 2) and taken in by the palletbuffer 19 so that it is transferred to the parts pallet positioning unit25 by the robot 10.

If, on the contrary, the discrimination reveals that the tray T carryingthe necessary parts has reached the pallet lifter 20, it is taken andpositioned in the assembling order to the elevator units 21a and 21b,unlike the case of the pallet P.

On the other hand, the assembling pallet P having been conveyed by theassembling conveyor 54 is positioned by the pallet positioning unit 17.In this state, the assembling of the predetermined parts are started forthe work W on the assembling pallet P. At this assembling time, thetrays T are circulated in the assembling order in the elevator units 21aand 21b of the parts feeding unit 200 and are positioned in determinedpositions DP. As a result, ten kinds of parts, for example, can be fedto the pallet head 12 of the robot 12. In case the turret head 12 is tobe exchanged as the parts feeds of the elevator units 21a and 21b, it isreplaced by that which is stocked in the super-pallet changer 15, toprepare the next assembling operations. When the tray T has its partsexhausted as the assembly proceeds, it is discharged to the lower stageconveyor 14b of the parts feeding conveyor 14.

In case the pallet P has its parts exhausted, on the other hand, thepallet P of FIG. 2 is transferred to the pallet buffer 19 by the robot10 and is returned to the pallet lifter 20 and discharged to the upperstage conveyor 14a of the parts feeding conveyor 14 by the action of thepallet take-in pusher 18. When the tray T carrying no parts isdischarged to the lower stage conveyor 14b, the remaining trays T in theelevator unit 21a are held on standby without any circulation till theelevator unit 21a is fed with a new tray T carrying the parts. When thisnew tray T is fed, the individual trays T are then circulated and fed atall times without any change in the assembling steps so that themulti-kind and small-quantity production can be accomplished.

Parts Feeding Unit 200

FIG. 5 shows a take-in unit 200 of the parts feeding unit 200, as shownin FIG. 1, for taking in the trays T, and FIG. 6 shows a take-out unit200B for the trays T. These take-in unit 200 and take-out unit 200B arethe parts feeding units to be used in combination, as shown in FIG. 2,for circulating the trays T, and are arranged in the robot cell 51, asshown in FIGS. 2 to 4.

This parts feeding unit 200 is schematically composed, as shown in FIGS.5 and 6, of the parts feeding conveyor 14 and transferring/positioningmeans 200C for the trays T. This transferring/positioning means 200C iscomposed of: the take-in unit 200A acting as a first transfer unit forthe trays T; the take-out unit 200B acting as a second transfer unit forthe trays T; and a positioning unit 200D for the trays T.

The parts feeding unit 200 takes in the trays T carrying the parts ofthe kind necessary for one robot cell 51, e.g., ten kinds of parts fromthe upper stage conveyor 14a of the parts feeding conveyor 14. Moreover,the plurality of trays T thus taken in are circulated in the take-inunit 200A and the take-out unit 200B of the parts feeding unit 200 sothat the trays having the parts unloaded therefrom can be discharged tothe lower stage conveyor 14b. As shown in FIGS. 5 and 6, the elevatorunit 21a constitutes the circulation conveyor at the righthand (R) side,and the elevator unit 21b corresponds to the circulation conveyor at thelefthand (L) side. These elevator units 21a and 21b are givensubstantially the same constructions.

Parts Feeding Conveyor 14

As shown in FIG. 6, over each of the elevator units 21a and 21b, thereis disposed the positioning unit 200D for the trays T. As shown in FIG.2, this positioning unit 200D is one for positioning the trays T in thedetermined position DP within the operating range of the robot 10. Theparts feeding conveyor 14, as shown in FIG. 5, is equipped with theupper stage conveyor 14a and the lower stage conveyor 14b. Of these, theupper stage conveyor 14a is shown in FIG. 7, whereas the lower stageconveyor 14b is shown in FIG. 8. The upper stage conveyor 14a of FIG. 7is one for introducing the trays T and is equipped with the traydetecting unit 20 and the conveyor lifters 53 and 51 to convey the traysT in the direction of arrow A1.

On the other hand, the lower stage conveyor 14b of FIG. 8 is one fordischarging the trays T and is equipped with lifters 63 and 61. Thelifter 53 of FIG. 7 and the lifter 63 of FIG. 8 correspond to theelevator unit 21b of FIG. 5, as located at the lefthand side. On theother hand, the lifter 51 of FIG. 7 and the lifter 61 of FIG. 8correspond to the elevator unit 21a, as located at the righthand side.The detecting unit 20 of FIG. 7 can detect the trays T and the pallets Pbeing conveyed, to discriminate the kinds of the devices, stations andparts.

Thus, the upper stage conveyor 14a of FIG. 7 discriminates and takes inthe necessary trays T. On the other hand, the lower stage conveyor 14breturns the trays T and receives the empty trays T for the elevatorunit. Since the elevator units 21a and 21b shown in FIGS. 5 and 6 aregiven the similar constructions, the structure of one elevator unit 21will be described with reference to FIGS. 9 to 11.

FIG. 9 shows the elevator unit 21a, which is equipped with the take-inunit 200A as the first transfer unit and the take-out unit 200B as thesecond transfer unit. Moreover, FIG. 10 shows the components of thetake-in unit 200A, and FIG. 11 shows the components of the take-out unit200B.

Take-in Unit 200A for Trays T

First of all, the take-in unit 200A will be described with reference toFIGS. 9 and 10.

This take-in unit 200A is positioned above the upper stage conveyor 14a.Over the lifter 51 of the upper stage conveyor 14a, there are disposedthe separator 52, the elevator hanger 53 and the tray setter 55.

The separator 52 can be opened and closed in the directions of arrows Xto retain or release the tray T.

The tray setter 55 is positioned above a support 72 so that it isenabled to retain or release the tray by opening or closing its pawls55a and 55b.

On the other hand, the elevator hanger 53 can move up and down along thesupport 72 in the directions of arrows Z. The elevator hanger 53 isenabled to retain or release the tray T by opening or closing its pawls53a in the direction of arrows.

In addition, the tray pusher 56 is provided in association with the traysetter 55. The tray pusher 56 can be moved in the directions of arrows Yto move the tray T held by the tray setter 55 toward the tray setter 57of the take-out unit 200B.

Take-out Unit 200B for Trays T

Here will be described the take-out unit 200B with reference to FIGS. 9and 11.

The take-out unit 200B is composed of a tray setter 57, an elevatorhanger 61, a return elevator 60, a return separator 58 and a support 70.The tray setter 57 is also known as a "take-out upper stage separator"and is enabled to retain or release the tray T by opening or closing itspawls 57a.

This tray setter 57 forms part of the aforementioned positioning unit200D for the trays T. The tray setter 57 is enabled to retain or releasethe tray T by opening or closing in the directions of arrows. Moreover,the return separator 58 is also called the "take-out intermediateseparator" and is enabled to retain or release the tray T by opening orclosing in the directions of arrows, as shown in FIG. 9. The elevatorhanger 61 of FIG. 11 is formed with pawls 61a so that it is enabled toretain or release the tray T by opening or closing its pawls 61a.

The return elevator 60 of the take-out unit 200B, as shown in FIG. 12,can move in the Z directions between positions P1 and P2 of FIG. 9 alongthe support 70. In the state of FIG. 12, there are placed on the returnelevator 60 the guides 60a, on which is carried the tray T, as indicatedby double-dotted lines. The return elevator 60 is equipped with thetake-out pusher 59 called the "return pusher".

This take-out pusher 59 can push the tray T in the direction of arrowE1, as shown in FIG. 9, to the separator 52 of the take-in unit 200A. Inshort, the tray T is returned from the take-out unit 200B to the take-inunit 200A of FIG. 9. In case, moreover, the tray T is to be returned tothe separator 52 of the take-in unit 200A so that it may be circulatedbetween the take-in unit 200A and the take-out unit 200B, the returnelevator 60 is positioned at the position P1, as shown in FIG. 9.

In case, on the contrary, the return elevator 60 of FIG. 2 is in theposition P2, the empty tray T placed on the return elevator but havingno parts can be discharged or let off to the side of the return lifter61 of FIG. 9 by actuating the return pusher 59.

Reference will be made to FIGS. 13 to 15.

FIG. 13 shows an example of the structure of the elevator hanger 53 atthe side of the take-in unit 200A of FIG. 10 and the elevator hanger 61at the side of the take-out unit 200B of FIG. 11. The tray T is placedon the pawls 53a and 61a of the hangers 53 and 61. These hangers 53 and61 can be opened and closed in the directions of arrows X, for example.The individually two, i.e., totally four hangers 53 and 61 are arrangedin the elevator units 21a and 21b, as shown in FIG. 28.

FIG. 14 shows an example of the upper stage separator 55 and the lowerstage separator 52 of the take-in unit of FIG. 10 and the upper stageseparator 57 and the intermediate separator 58 of FIG. 11.

Positioning Unit 200D

FIG. 15 shows a construction of the positioning unit 200D disposed inthe upper stage separator 57 of FIG. 11.

Specifically, this positioning unit 200D is composed of an X-directionpusher 201, an X-direction positioning block 203 and a Y-directionpositioning block 205. Moreover, the tray T, as pushed in the directionof arrow Y by the take-in pusher 56 of FIGS. 10 and 15, is pushed ontothe Y-direction positioning block 205. By actuating the X-directionpusher 201, moreover, the tray T is pushed onto the X-directionpositioning block 203.

As a result, the tray T can be completely positioned in the X- andY-directions. This positioning unit 200D is within the operating rangeof the robot 10 of FIG. 2 so that the hands of the robot 10 can pick upthe parts in the positioned tray T.

Reference will be made to FIG. 16. The support 72 of FIG. 16 shows asensor for detecting the position of the hanger 53 of the take-in unit200A. The support 72 is equipped with a hanger upper stage stop positionsensor 72a, a stock area position sensor 72b, a hanger lower stage stopposition sensor 72c, an upper stage limit sensor 72d and a lower stagelimit sensor 72e.

The hanger upper stage stop position sensor 72a is constructed, as shownin FIG. 17. Specifically, this sensor 72a detects the take-out stopposition of the tray T to the upper stage separator 55 when a sheet oftray T is stocked on the hanger 53 of the take-in unit 200A of FIG. 9.The sensor 72a comes into contact with a dog D, when the lower face ofthe tray T of FIG. 17 is short of the tray receiving face of the upperstage separator 55 by 0 to 1 mm, for example, so that it is turned ON.

The hanger stock area position sensor 72b of FIG. 18 detects whether ornot the hanger 53 stands by in a position away of interference with thetray T on the hanger 53, when the next tray T is brought into the lowerstage separator 52 of FIG. 9.

The hanger lower stage stop position sensor 72c shown in FIG. 19 detectsthe stop position of the hanger 53 when the hanger 53 of FIG. 9 takesthe tray T on the lower stage separator 52. When the sensor 72c isturned ON while the hanger 53 descending, the descending speed of thehanger 53 is switched from high to row values. Then, the sensor 72c isturned OFF to stop the descending movement. While the hanger 53 isdescending, the sensor 72c is turned OFF when the lower face of the trayT is short of the tray receiving face of the lower stage separator 52 by0 to 1 mm.

The hanger upper limit sensor 72d shown in FIG. 20 comes into abutmentagainst the dog D and is turned OFF, when the lower face of the tray Truns over the receiving face of the upper stage separator 55 by about 5mm.

The hanger lower limit sensor 72e of FIG. 21 comes into abutment againstthe dog D and is turned OFF, when the tray receiving faces of the pawls53a of the hanger 53 runs over the receiving faces of the lower stageseparator 52 of FIG. 10 by about 5 mm.

Next, there are shown in FIG. 22 a set of sensors which are mounted onthe support 70 of the take-out unit 200B. The support 70 is equippedwith a hanger standby position sensor 70a, a hanger intermediate stagestop position sensor 70b, a hanger lower stage stop position sensor 70c,an upper limit sensor 70d and a lower limit sensor 70e.

The hanger standby position sensor 70a, as shown in FIG. 23, detects thestop position for the standby of the hanger below the upper stageseparator 57 while no tray T is stocked for the hanger 61 of thetake-out unit 200B of FIG. 11. The sensor 70a comes into abutmentagainst the dog D and is turned ON when the tray receiving faces of thepawls 61a of the hanger 61 are short of the receiving face of the upperstage separator of FIG. 23 by 18 mm, for example.

The hanger intermediate stage stop position sensor 70b of FIG. 24detects the stop position of the hanger 61 when the hanger 61 takes thetray T on the intermediate stage separator 58 of FIG. 11. This sensor70b comes into abutment against the dog D and is turned ON when the trayreceiving faces of the pawls 61a of the hanger 61 are short of the lowerface of the tray T on the intermediate stage sensor 58 by 12 mm, forexample.

The hanger lower stage stop position sensor 70c of FIG. 25 detects thestop position of the hanger 61 when the tray T is placed on the guiderails 60a of the tray return unit 60. The sensor 70c is turned ON, whenthe hanger 61 descends, to switch the descending speed from higher tolower values, and is turned OFF by the dog D to stop the descendingmovement.

The hanger upper limit sensor 70d, as shown in FIG. 26, detects theoverrun of the stop position of the hanger 61 with respect to the upperstage separator 57. The sensor 70d is turned OFF by the dog D when thelower face of the tray T overruns the receiving face of the upper stageseparator 57 by 6 mm, for example.

The hanger lower limit sensor 70e of FIG. 27 detects the overrun in thelower stage stop position. The sensor 70e comes into abutment againstthe dog D and is turned OFF when the tray receiving faces of the pawls61a of the hanger 61 overrun the guide rails 60a of the tray returnportion 60 by 5 mm, for example.

Next, FIG. 29 is a top plan view showing the elevator units 21a and 21band a set of sensors for detecting the tray T.

In FIG. 28, there are shown: a take-out upper stage separator traydetecting sensor 101; a take-out intermediate separator tray detectingsensor 103; a take-out stock tray upper end detecting sensor 102; atake-in stock tray upper end detecting sensor 104; a take-in hangerstock deceleration detecting sensor 105; a take-in upper stage separatortray detecting sensor 106; and a take-in lower stage separator trayarrival sensor 107.

As shown in FIG. 28, the sensor 101 detects both the arrival of the trayT at the upper stage separator 57 of the take-out unit 200B from thetake-in unit 200A and the lift of the tray by the hanger 61 at thetake-out time of the tray T. The sensor 101 is turned ON, when the trayT is placed on the upper stage separator 57 of the take-out unit 200B,and OFF when the tray T is floated by about 1 mm from the upper stageseparator 57.

The sensors 102 and 104 of FIG. 28 detect the standby positions of thehangers 53 and 61 at the positions short of the upper stage separator 57if the trays T are stocked on the hangers.

The sensors 104 and 106 detect the trays T when one is taken out fromeach of the trays T stacked on the take-out intermediate stage separator58 and the take-in upper stage separator 57.

The sensor 105 of FIG. 28 detects the deceleration position of thehanger 53 of the take-in unit 200A when the tray on the hanger 53 is tobe stacked on the trays T on the lower stage separator 52, in case thetray T on the lower stage separator 52 is to be taken while the tray Tis stocked on the hanger 53.

The sensor 107 detects the arrival of the tray T which is returned fromthe take-out lifter to the lower stage separator.

Example of Operations of Parts Feeding Unit 200

Here will be described an example of the operations of the parts feedingunit 200 with reference to FIGS. 31 to 37.

FIG. 31 shows the take-in unit 200A and the take-out unit 200B of theparts feeding unit 200, the parts feeding conveyor 104, and the robot 10for taking the parts PB.

In connection with these components, the operations of FIGS. 31 to 37will be described.

In FIG. 31, the lower stage separator 52, the elevator hanger 53 and theupper stage separator 55 of the take-in unit 200A are respectivelyarranged with trays T1 to T3. In FIG. 31, first of all, each of thetrays T1 to T3 carries a plurality of, e.g., four parts PB.

As shown in FIG. 31, on the other hand, there is placed on the upperstage separator 57 of the take-out unit 200B a tray T4 which carries aplurality of, e.g., four parts PB. This tray T4 is thus positioned inthe positioning unit 200D.

In short, in the state of FIG. 31, the plurality of, e.g., four trays T1to T4 are circulated in the take-in unit 200A and the take-out unit200B.

One part PB of the tray T4 is taken up by the turret head 12 of therobot 10, as shown in FIG. 31, and is turned by the robot 1, as shown inFIG. 32. Then, the robot 10 assembles its held part PB with the work Won the assembling pallet PA which is arranged in the assembling palletpositioning unit 17 of FIG. 2. As a result, a plurality of, e.g., threeparts PB are left on the tray T4.

When a predetermined part PB is thus taken out of the tray T which ispositioned in the determined position DP of the positioning unit 200D ofFIG. 31, the hanger 61 rises in the direction of arrow Z1 to take thetray T4 on the upper stage separator 57. This upper stage separator 57is opened to hand the tray T4 to the hanger 61. This hanger 61 descendsin the direction of arrow Z2. As a result, the tray T4 is placed on thereturn elevator 60, as shown in FIG. 32. Then, the hanger 61 ascends inthe Z1 direction until it stands by in the position, as indicated bydouble-dotted lines in FIG. 32.

Reverting to FIG. 31, on the other hand, the tray T3 placed on the upperstage separator 55 of the take-in unit 200A of FIG. 31 is pushed to thedetermined position DP at the side of the empty upper stage separator 57by the action of the pusher 56 of the positioning unit 200D. As aresult, as shown in FIG. 32, the tray T4 is transferred to the upperstage separator 57 of the take-out unit 200B and is positioned by thepositioning unit 200D.

Since the upper stage separator 55 is emptied, as shown in FIG. 32, thehanger 53 rises in the Z1 direction to transfer the tray T2 to thehanger 55. At this time, this hanger 55 is open so that it can be closedto carry the tray T2.

Next, as shown in FIG. 33, the emptied hanger 53 descends toward thelower stage separator 52 to lift a thinner tray T21 and the tray T1 in astacked state in the Z1 direction.

As a result, the hanger 53 is positioned, as indicated by broken linesin FIG. 33, to position the tray T21 and the tray T2 just below the trayT2.

As shown in FIG. 34, on the other hand, the tray T4 on the returnelevator 60 is transferred to the emptied lower stage separator 52 byactuating the pusher 59 of the take-out unit 200B. Thus, the trays T1,T21, T2, T3 and T4 can be sequentially circulated and positioned in thepositioning unit 200D. As a result, the pallet head 12 of the robot 10can take out the necessary parts PB from the necessary tray T.

Reference will be made on FIG. 35.

In case the take-up (or pick-up) operations of the parts PB advances sofar that one pallet TN has its all parts PB taken out to become empty,the return elevator 60 descends from the position P1 of FIG. 34 and ispositioned in the position P2 of FIG. 35.

As the pusher 59 acts, the emptied tray TN is transferred to the lifter61 of the lower stage conveyor 104b. As the lower stage conveyor 104bmoves in the direction of arrow A3 (from this side to the other side ofthe drawing), the tray TN is conveyed by the conveyor unit 53 of FIG. 1.

In case the emptied tray TN is thus discharged, a new tray T0 carryingadditional parts PB is taken from the take-in unit 200A and iscirculated between the take-in unit 200A and the take-out unit 200B.

This new tray T0 is taken, as shown in FIGS. 36 and 37. Specifically,the upper stage conveyor 104a conveys the new tray T0 carrying the partsPB in the direction of arrow A1 (to this side of the drawing). Then, thekind of this tray T0 is decided by the pallet lift 20 of FIG. 2. If thisdecision reveals that the tray T0 is one carrying the necessary parts,the tray T0 should be circulated and is positioned on the lifter 51.

This lifter 51 lifts up the new tray T0 in the Z1 direction. The tray T0thus lifted up is placed on the separator 52 and is separated from thelifter 51.

Next, the hanger 53 descends, while having its pawls 53a and 53b (asshown in FIG. 9) opened, to the lower stage separator 52 carrying thenew tray T0, and has its pawls 53a closed to lift up the new tray T0 inthe Z1 direction.

Since another tray T is placed on the upper stage separator 55 in theexample of FIG. 36, the elevator hanger 53 stops just at this side ofthe upper stage separator 55 so that no interference may occur. Then,the elevator hanger 53 stands by till the tray T on the upper stageseparator 55 is transferred to the next upper stage separator 57.

Incidentally, the next tray stands by, if necessary, on the returnelevator 60 till there newly comes the tray carrying the parts of thesame kind as that of the parts of the tray TN returned, as shown in FIG.35. Moreover, the next and later trays T can be stopped over the returnseparator 58 shown in FIG. 9, so that the parts can be fed withoutdisturbing the sequential circulation of the trays T.

As has been described hereinbefore, ten or more kinds of parts can berepeatedly fed to the robot 10 by the tray T, and four kinds of parts,for example, can be fed by the pallets which are supplied from the partsfeeders 52 of FIG. 1. According to this embodiment, therefore, a totalof fourteen kinds of parts can be fed to the robots 10 and assembledwith the works.

The exchange of the kinds of the devices to be assembled can be effectedby exchanging those trays and pallets and the pallet head to effect themulti-kind and small-quantity production.

By providing each assembling robot cell with that circulation type partsfeeding apparatus, moreover, the apparatus size and the line space canbe reduced by 50% or more, as compared with the prior art, to spare thespace.

Moreover, the stock of the parts in the assembly line can be reduced.

Still moreover, the capacity of the utilities such as the air pressureor the electric power can be reduced to spare the power consumption.

As described above, still moreover, the exchange of the device kinds canbe easily coped with to improve the flexibility. It is further possibleto improve the quality of the assembly.

Incidentally, the present invention should not be limited to theembodiment thus far described.

In the foregoing embodiment, the take-in unit and the take-out unit areso circulated to move the trays in the vertically upward direction andin the vertically downward direction. The circulation should not limitedthereto, but there may naturally be formed a trapezoidal or rhombiccirculation loop, along which those units ascend or descend at an anglewith respect to the vertical direction.

Moreover, although the assembly robot of the embodiment is equipped withthe turret head for taking out the parts, it should not be limitedthereto but may be equipped with a robot hand.

Although the parts feeding unit of the embodiment is equipped with thetwo pairs of take-in units and take-out units, it should not be limitedthereto but may be equipped with one pair or three pairs or more oftake-in units and take-out units.

As has been described hereinbefore, according to the present invention,it is possible to spare the space, to reduce the parts stock in the lineand to easily cope with the exchange of the device kinds.

What is claimed is:
 1. A parts feeding apparatus for feeding parts,which are carried on a tray, to an assembling body for assembly,comprising:conveyor means for conveying said parts carrying tray to andfrom said assembling body; and transferring and positioning means fortransferring and positioning said parts carrying tray;wherein saidtransferring and positioning means includes: a first transfer unit fortransferring said parts carrying tray upward in a first direction fromsaid conveyor means; a positioning unit for positioning said partscarrying tray from said first transfer unit into a determined positionwithin an assembling range of said assembling body; and a secondtransfer unit for transferring said parts carrying tray positioned insaid determined position, downward in a second direction reversed fromsaid first direction, to said first transfer unit or for dischargingsaid tray emptied of said parts to said conveyor means;wherein saidconveyor means includes: an introducing conveyor arranged for feedingsaid first transfer unit with said parts carrying tray; and adischarging conveyor for discharging said tray emptied of said partsfrom said second transfer unit; and wherein said introducing conveyorand said discharging conveyor are arranged one over the other, andwherein the direction for said introducing conveyor to introduce saidtray and the direction for said discharging conveyor to discharge saidtray are made to intersect the moving directions of said tray includingsaid first direction and said second direction in said transferring andpositioning means.